My function call does not return the value

Question

This is my code, i'm getting the values printed in console, but it's not returning that value.

async function fetchData(uid) {                                           
  return firebase.firestore().collection('users_info')
         .where("uid","==",uid).get()
         .then( async function(querySnapshot) {
             var usr;         
             querySnapshot.forEach(async function(doc) {           
             usr = await doc.data().name;
             console.log(usr);
             return  usr;
         });      
    });       
}

`return` in your promise callback function only returns the callback but not `fetchData` — vizsatiz, Jun 16 '20 at 10:41
`.forEach()` typically ignores the return value of the callback. — Andreas, Jun 16 '20 at 10:52
If you're going to declare a function `async`, then there is no need to use `then` for the promises inside it. That's what `await` is for. — Doug Stevenson, Jun 16 '20 at 15:54

score 1 · Accepted Answer · edited Jun 16 '20 at 15:54

Since you are using a forEach I am assuming you are dealing with more than one data item. In that case, it might be better to push them all into an array and return that. I am adding a slight modification of your snippet bellow. I think this should do the trick.

  async function fetchData(uid) {
    return firebase.firestore()
      .collection('users_info')
      .where("uid", "==", uid)
      .get()
      .then(async function(querySnapshot) {
        var usr = [];
        querySnapshot.forEach(async function(doc) {
           const temp = await doc.data().name);
          usr.push(await doc.data().name))
        });
      return usr;
    })
  }

it's working , need to fix some small syntax error. – Harish Jun 16 '20 at 12:44 — Harish, Jun 16 '20 at 12:44

score 0 · Answer 2 · answered Jun 16 '20 at 11:31

Two things - first, you need to return a promise, if your function itself is doing async work that needs it's own callback to be continued from. See Return from a promise then().

Also, foreach is not necessarily used to return a collection of transformed values, which seems to be what you're trying to do there. I'd replace it with map if you can.

My function call does not return the value

2 Answers2